The present invention relates to a method of manufacturing a semiconductor material for use in light-emitting devices such as light-emitting diodes, laser diodes, and the like and, more particularly, to a method of manufacturing group II-VI compound semiconductors which present the p-type conduction.
The group II-VI compound semiconductors consisting of a group II element such as mercury (Hg), cadmium (Cd), zinc (Zn), or the like and a group VI element such as sulfer (S), selenium (Se), tellurium (Te), or the like are suitable as a material to constitute light-emitting devices such as light-emitting diodes, laser diodes, and the like. However, in group II-VI compound semiconductors, in general, it is difficult to obtain a crystal which presents p-type conduction, so that a pn-junction light-emitting device having a high efficiency has not been realized yet. Hitherto, as an attempt to obtain a group II-VI compound semiconductor of the p-type, there has been known the method whereby phosphorus (P) is doped as an impurity to realize the p-type in the step of the crystal growth by a molecular-beam epitaxy method (for example, refer to "Journal of Crystal Growth", Vol. 72, No. 1/2 (1985), pages 31-40). In this method, Zn, Se, and Zn.sub.3 P.sub.2 are respectively heated and evaporated under vacuum, thereby forming a thin film of ZnSe crystal including P on the substrate.
However, according to such a conventional method, since the vapor pressure of P is high, P deposited on the substrate is reevaporated, so that a sufficient amount of P cannot be doped. Thus, it is impossible to produce a crystal which presents p-type conduction.